This disclosure relates to a developing device that forms a toner image by feeding toner toward an electrostatic latent image formed on a circumferential surface of a photosensitive drum by electrophotography and an image forming apparatus having the same, and particularly to a technique for preventing leakage of toner on a circumferential surface of a developing sleeve.
In such an electrophotographic image forming apparatus, a toner image is formed by feeding toner from a developing device toward an electrostatic latent image formed on a surface of a photosensitive drum. Such a developing device has a developing roller made up of a magnet roller and a developing sleeve, forms a toner layer on a circumferential surface of the developing sleeve, and feeds the toner from the developing sleeve to the surface of the photosensitive drum. The developing sleeve of the developing device is provided with seal members at both ends thereof in a rotation axis direction thereof. The seal members are opposite to the circumferential surface of the developing sleeve, and inhibit the toner on the circumferential surface from moving to the ends in the rotation axis direction and leaking out of the ends. Thus, a developing device A is proposed in which a root part guiding the toner on the developing sleeve into a developing zone is provided for an inner circumferential surface of each seal member in order to more reliably prevent the leakage of the toner.